Known print hammer assemblies commonly used in high speed line printers have generally provided flexurally mounted interposer-type hammers and separate damping means associated with armature-actuators that are cooperably disposed relative to the hammers. In these known assemblies a stationary solenoid is generally provided for each of the hammers in the line printer, the energization of the solenoid serving to magnetically attract the armature-actuator to impact the hammer into printing contact with a print media, ribbon and selectively positioned type character located in the printing position. Following the impacting of the hammer against the selectively positioned type character, which may be arranged on a drum, chain or band, the rebounding effect of the impacting of the hammer has generally been absorbed and dampened by separate stationary damping means such that the hammer will not rebound against the media and type character to produce what is known as "shadow printing".
Typical of these known print hammer assemblies are those disclosed in U.S. Pats. Nos. 3,335,659; 3,351,006 and 3,670,647. In U.S. Pat. No. 3,335,659 to Schacht et al. the print hammer assembly is comprised of a flexurally mounted print hammer, a pair of integrally formed armature yokes disposed in cooperating relationship with a stationary solenoid, and separate elastic damping means that is effectively assisted by prolonging the energization of the solenoid beyond the instant of print hammer impact.
In U.S. Pat. No. 3,351,006 to Belson the print hammer assembly is comprised of a flexurally mounted print hammer, a separate pivotal armature actuator associated with a stationary solenoid, and separate damping means consisting of a magnet that dampens the return impacting force of the actuator against an associated backstop. In U.S. Pat. No. 3,670,647 to Funk et al., the print hammer assembly is comprised of a flexurally mounted print hammer, a separate pivotally mounted armature actuator, and separate elastic damping means which, as in Schacht et al., is effectively assisted by prolonging the energization of the solenoid beyond the instant of print hammer impacting.
Although these known print hammer assemblies have proven to be effective when used in the particular line printer environments for which they were intended, and particularly in relatively high priced data processing printing peripherals, they have been found to be too expensive for use in lower priced line printers wherein the quality of the printed result is not to be sacrificed, but wherein initial and maintenance economies are held to be controlling. It has been found, for example, that significant economies in initial manufacturing costs cannot be achieved through the perpetuation of the print hammer assembly concept described supra, wherein the essential elements of a print hammer, an armature actuator, and damping means are separately manufactured and assembled together either directly into the line printer or into subassemblies to be later installed within the printer. Characteristically, the print hammer assembly concept has necessitated the employment of parts of substantially greater size and weight than would be functionally required by the assembly itself, but that would lend themselves to various machining and assembly operations in the manufacturing facility. It will also be apparent that the practice of prolonging the energization of the solenoid beyond the instant of print hammer impact, although effective as an aid or substitute for the damping means element, serves to increase the duty cycle of the solenoid and thus to interfere with the realization of optimized maintenance economies.